Musings on Science

Spotless Minds

It’s a sobering paradox that memories are simultaneously our most precious and least robust possessions. It’s been shown that, while a majority of people surveyed believe their memories to be perfect, the substance of our memories changes every time we recall them. Recent research has apparently done a lot more: we’ve now identified a gene, a protein and a cluster of neurons that directly affect the way memories are stored and retrieved.

It’s interesting that these various researchers attacked the problem of memory from such different angles and arrived at such startling, definite conclusions. Also worthy of note, to me, is that three major players of the pathway between genes and cells were involved. There are apparently several stages between our genetic code and the more directly measurable neurons where we could potentially fiddle with our minds, and I fully expect that sentence to strike anyone with terrified excitement.

The Neuron

I’ve come across several fascinating pieces on this lately. The one that first caught my eye was this study by MIT researchers, who used light pulses to stimulate a memory of a fear in mice. That technique — called optogenetics, the process by which genes are engineered to respond to light — will need to be the subject of a whole new article by itself, but in the meantime, we’ll focus on the fact that specific sections of neurons in the hippocampus were triggered directly. This article in ExtremeTech and this other one in CNet both include some speculation about the ramifications of this technology, but considering that a laser needs to be pointed directly into the skull (and therefore a hole needs to be drilled into the subject’s head), it’s not quite at the level of Matrix kung-fu learning yet.

Just today, while trying to find those articles, I came across some research that sounds even more interesting, with techniques that are certainly more “programmable”. Researchers think that an “information storage lattice” could be what’s preserving memories inside neurons. Apparently these lattices could be holding anywhere from 64 to 5281 bits of data, and could be performing operations based on well-known logic gates like AND, NOR and so on.

The Protein

The March issue of Wiredfeatured the “forgetting pill” — a chemical that could directly alter or even erase specific memories. Neurologist Todd Sacktor, in the 1980s, had discovered that an enzyme called PKMzeta facilitates the remembrance of long-term memories. It apparently increases communication between neurons, causing them to excite each other more easily and therefore preserve memories. By injecting a relatively common inhibitor, Sacktor could temporarily halt the production of PKMzeta, and, therefore, destroy the memory itself.

The same article mentions that a previous scientific study conducted by Karim Nader in the 1990s showed how inhibiting all protein synthesis could permanently delete a memory. Sacktor had more than confirmed that hypothesis. What’s particularly fascinating is that basic premise behind these experiments: that the memories we hold so dear are basically a function of protein processes, that when we recall, the memory has to be regenerated each time. Wipe out the crucial part of the step — protein production — and the memory is essentially irretrievable.

The Gene

Another article from ExtremeTech (this one isn’t particularly well-written; knocking out the memory gene doesn’t just have implications for fearlessness) describes how disabling the gene controlling for the Npsa4 transcription factor disrupts the memory consolidation process. The MIT press release is far more informative about how Npsa4 plays a role, but the message is still the same — genetic engineering that affects the whole process of remembering is entirely possible. It’s not just fear; researchers believe Npsa4 could be just as important to other forms of learning.

The last part of the press release provides a particularly tantalizing link back to the Wired article: can Npsa4 be used to erase memories, instead of just preventing them from being formed?

Evaluation

With this plethora of studies focused on the process of memory, how do we decide which is most viable (leaving the question of ethics for later)?

Stimulating sections of the neurons with light would be instantaneous and effective, and possibly would leave less long-term or chemical impact on the body. On the other hand, the stimulation would have to be incredibly precise so as not to damage any other memory. The researchers, according to the CNN article, stimulated parts of the hippocampus which were active when the mice were learning a new environment. The hippocampus, however, is just one of the areas involved in memory storage. And it might be an easier feat to distinguish which specific memory to target in mice, compared to humans. It’s probably also significant that the researchers observed the changes in the brains of the mice as they went through the experiment, but if we were to delete a memory in the human brain we would have to first discover where the memory was situated. We could conceivably ask test subjects to recall the memory as precisely as they knew how and detect changes in brain activity by using an fMRI.

On the other hand, chemical means of deleting a memory might be more feasible and less frightening to those undergoing the procedure; we’re weighing drilling a hole through the skull against the ingestion of a simple pill. With complicated protein pathways, however, there’s a possibility that disrupting the protein that encodes long-term memory could have side effects that may make the procedure too risky. I would have wished for the Wired piece to have more information about the physiological risks involved in a procedure like this, but it’s possible the researchers haven’t had the opportunity to explore that.

Of the three, the genetic trigger in the form of the gene controlling Npsa4 seems to be the most wide-ranging and least specific. It’s clear now that the gene is tightly coupled with the process of long-term learning and memory, but we wouldn’t be able to, for instance, wipe out a specific memory. We could, perhaps, prevent memories from forming during a specific time period, but that would imply a lengthy process of genetic engineering. This, however, might be able to shed some light on the difference between fast and slow learners and how we absorb information — perhaps this will be useful in studying development and growth in children and what would disrupt that process.

The Ethics

There’s something very irresponsible-sounding about the idea of simply erasing select bits of our memory. After all, don’t we take it for granted that our experiences make us who we are? No matter how terrible the trauma or breakup or pain, we reason, the incident must have played a crucial role in our development.

But the Wired article makes a reasonable case for “curing” certain kinds of memory, or at least erasing the debilitating effects of them. Ecstasy, for instance, was used to help patients deal with traumatic events by helping them associate the memory with the positive feelings that the drug created. If these methods for erasing or reducing the longevity of memories could be employed to help severely mentally disturbed patients, I could see the point in research like this.

Whether we should erase memories wholesale, simply because we can, is another argument entirely. Some might point out that our brains are already capable of suppressing or distorting memories as a coping mechanism, and therefore that we’re simply speeding up a naturally occurring process; opponents of that view might say that we just don’t know enough about the side-effects, not only of the chemicals involved in forgetting, but in the psychology of it. Who would we be, if we knew we had large blank holes in our memories? Would we also attempt to remember the rationale behind wanting to forget those incidents? What if the very act of forgetting endangered our mental stability?